This is Steve Ember with the VOA Special English AgricultureReport.
From the beginning of human history, people have used oils fromseeds and nuts. Most of the time these oils are used as food,especially in cooking. But sometimes they have other uses. Forexample, oils are found in paint and in cleaning products, likesoap.
Oil is separated from seeds by using pressure. A machine called apress is often used. Sometimes it is surprising to learn how muchoil the seeds contain. These common seeds all contain at leastfifty-percent oil: olives, groundnuts, sesame, cotton and sunflower.
The soybean is an important seed around the world, but it is onlytwenty percent oil. So chemicals are needed to release oil fromsoybeans.
The first step in pressing the oil from seeds is to crush theseeds between two stones. A cloth container or bag is filled withthe crushed seeds. Then the bag is hung up. Some of the oil willflow out of the bag and can be collected. But some oil will remainin the crushed seeds inside the bag. The easiest way to get the restof the oil out is to place heavy rocks on the crushed material.
Another method is to place several cloth bags on top of eachother in a box. Then a long wooden stick is used to slowly push aheavy cover down on the bags. Great pressure is produced in thisway. Much greater pressure can be produced by using a machine, ahydraulic jack. The greater the pressure, the more oil will beproduced.
Oil can also be collected with small, hand-operated machines.Small presses are important in areas where electricity or gasolinecannot be used. They are also a good way to test if a local marketfor oil exists.
Small batch presses can be made of local materials. Their cost islow. They are not difficult to operate. And they are easy to repair.The small presses produce good quality oil. But the work is hard.And getting all the oil from the seeds can be difficult.
A system can be set up to press together an amount of seeds atdifferent times of the day. But if there is a large supply of seeds,then large, powered presses that can operate all day are needed.
You can get more information about collecting oil from seeds fromthe group VITA, Volunteers in Technical Assistance. VITA is on theInternet at v-i-t-a dot o-r-g.
This VOA Special English Agriculture Report was written by GaryGarriott. This is Steve Ember.